LeetCode题解(0958)：判断二叉树是否为完全二叉树(Python)

题目：​​原题链接​​（中等）

标签：树、二叉树、广度优先搜索

解法一：

class Solution:
    def isCompleteTree(self, root: TreeNode) -> bool:
        already_finish = False
        queue = [root]
        for node in queue:
            if node.left:
                if already_finish:
                    return False
                queue.append(node.left)
            else:
                already_finish = True
            if node.right:
                if already_finish:
                    return False
                queue.append(node.right)
            else:
                already_finish = True

        return True